2014-10-28 08:23:28 UTC
WHAT SCIENTIFIC IDEA IS READY FOR RETIREMENT? Steve Giddings: "Spacetime. Physics has always been regarded as playing out on an underlying stage of space and time. Special relativity joined these into spacetime... (...) The apparent need to retire classical spacetime as a fundamental concept is profound..."
Nima Arkani-Hamed, 14:31 : "We strongly believe that spacetime doesn't really exist. (...) The slogan is that spacetime is doomed and something has to replace it."
NEW SCIENTIST: "Rethinking Einstein: The end of space-time. IT WAS a speech that changed the way we think of space and time. The year was 1908, and the German mathematician Hermann Minkowski had been trying to make sense of Albert Einstein's hot new idea - what we now know as special relativity - describing how things shrink as they move faster and time becomes distorted. "Henceforth space by itself and time by itself are doomed to fade into the mere shadows," Minkowski proclaimed, "and only a union of the two will preserve an independent reality." And so space-time - the malleable fabric whose geometry can be changed by the gravity of stars, planets and matter - was born. It is a concept that has served us well, but if physicist Petr Horava is right, it may be no more than a mirage. (...) For decades now, physicists have been stymied in their efforts to reconcile Einstein's general theory of relativity, which describes gravity, and quantum mechanics, which describes particles and forces (except gravity) on the smallest scales. The stumbling block lies with their conflicting views of space and time. As seen by quantum theory, space and time are a static backdrop against which particles move. In Einstein's theories, by contrast, not only are space and time inextricably linked, but the resulting space-time is moulded by the bodies within it. (...) Something has to give in this tussle between general relativity and quantum mechanics, and the smart money says that it's relativity that will be the loser."
"And by making the clock's tick relative - what happens simultaneously for one observer might seem sequential to another - Einstein's theory of special relativity not only destroyed any notion of absolute time but made time equivalent to a dimension in space: the future is already out there waiting for us; we just can't see it until we get there. This view is a logical and metaphysical dead end, says Smolin."
"Was Einstein wrong? At least in his understanding of time, Smolin argues, the great theorist of relativity was dead wrong. What is worse, by firmly enshrining his error in scientific orthodoxy, Einstein trapped his successors in insoluble dilemmas..."
Yet, while Einsteinians apparently want to reject spacetime, the wrong consequence of Einstein's 1905 two postulates, they still strongly believe that the postulates themselves are true:
QUESTION: Setting aside any other debates about relativity theory for the moment, why would the speed of light be absolute? No other speeds are absolute, that is, all other speeds do indeed change in relation to the speed of the observer, so it's always seemed a rather strange notion to me.
LEE SMOLIN: Special relativity works extremely well and the postulate of the invariance or universality of the speed of light is extremely well-tested. It might be wrong in the end but it is an extremely good approximation to reality.
QUESTION: So let me pick a bit more on Einstein and ask you this: You write (p. 56) that Einstein showed that simultaneity is relative. But the conclusion of the relativity of simultaneity flows necessarily from Einstein's postulates (that the speed of light is absolute and that the laws of nature are relative). So he didn't really show that simultaneity was relative - he assumed it. What do I have wrong here?
LEE SMOLIN: The relativity of simultaneity is a consequence of the two postulates that Einstein proposed and so it is deduced from the postulates. The postulates and their consequences are then checked experimentally and, so far, they hold remarkably well.
Nima Arkani-Hamed: "When first encountering relativity, what really struck me about it more than anything else was actually how incredibly simple the underlying ideas were. The big point wasn't hidden in some minutiae of some deep mathematics, or these stunning, very striking assumptions - that the speed of light is constant and that physics looks the same in all frames of reference - and from these two seemingly innocuous assumptions come this incredibly different worldview than the standard Newtonian picture of the world."
Conclusion: Spacetime is not and cannot be doomed in Einstein's schizophrenic world. Einsteinians are not going to reject it - making more money is the only goal of the current campaign:
QUANTUM MECHANICS AND SPACETIME IN THE 21ST CENTURY
NIMA ARKANI-HAMED, INSTITUTE FOR ADVANCED STUDY
THURSDAY, NOVEMBER 6, 2014 AT 7:00PM
PERIMETER INSTITUTE - 31 CAROLINE ST. N., WATERLOO
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